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discounted EARLY registration ends Dec 31, 2014
Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
Metabolic Modeling Tutorial
discounted EARLY registration ends Dec 31, 2014
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MetaCyc Enzyme: cystathionine γ-synthase / selenocystathione synthase

Gene: CGS1 Accession Number: AT3G01120 (MetaCyc)

Synonyms: MTO1, Methionine Overaccumulator 1, CGS

Species: Arabidopsis thaliana col

Subunit composition of cystathionine γ-synthase / selenocystathione synthase = [CGS1]4
         cystathionine γ-synthase = CGS1

Citations: [Ravanel98]

Locations: chloroplast

Map Position: [39,052 <- 41,935] (0.17 centisomes)

Molecular Weight of Polypeptide: 60.0 kD (from nucleotide sequence), 53 kD (experimental)

Molecular Weight of Multimer: 200 kD (experimental)

Unification Links: PhylomeDB:P55217 , Phytozome Plant Orthologs:At3g01120.1 , Pride:P55217 , Protein Model Portal:P55217 , SMR:P55217 , String:P55217 , TAIR:AT3G01120 , UniProt:P55217

Relationship Links: InterPro:IN-FAMILY:IPR000277 , InterPro:IN-FAMILY:IPR015421 , InterPro:IN-FAMILY:IPR015422 , InterPro:IN-FAMILY:IPR015424 , Panther:IN-FAMILY:PTHR11808 , Pfam:IN-FAMILY:PF01053 , Prosite:IN-FAMILY:PS00868

Gene-Reaction Schematic: ?

GO Terms:

Cellular Component: GO:0009507 - chloroplast


Enzymatic reaction of: cystathionine γ-synthase

EC Number: 2.5.1.-

L-cysteine + O-phospho-L-homoserine <=> L-cystathionine + phosphate

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction in which it was curated.

The reaction is favored in the direction shown.

In Pathways: superpathway of lysine, threonine and methionine biosynthesis II , methionine biosynthesis II

Summary:
There is no observed feedback inhibition for CGS in vitro. Propargylglycine (PAG) inhibits CGS by covalently binding to its active site. However the inhibition is not competitive in that the inactivation of the CGS enzyme is not reversible (even though the binding of PAG is reversible).

Cofactors or Prosthetic Groups: pyridoxal 5'-phosphate [Ravanel98]

Inhibitors (Irreversible): propargylglycine [Ravanel98]

Inhibitors (Unknown Mechanism): L-methionine [Kim02a]

Kinetic Parameters:

Substrate
Km (μM)
Citations
O-phospho-L-homoserine
2500.0
[Ravanel98]
L-cysteine
460.0
[Ravanel98]

pH(opt): 7.5


Enzymatic reaction of: selenocystathione synthase

EC Number: 2.5.1.-

L-selenocysteine + O-phospho-L-homoserine <=> L-selenocystathionine + phosphate

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction in which it was curated.

The reaction is favored in the direction shown.

In Pathways: superpathway of seleno-compound metabolism , seleno-amino acid biosynthesis

Summary:
This enzyme has not been shown to directly catalyze selenocystathionine production, nor has its activity on selenocysteine been demonstrated in Arabidopsis thaliana col. However, over-expression of this enzyme in Brassica juneca causes increased release of volatile selenocompounds [Van03]. This suggests that this reaction is rate-limiting in that species [Van03].

History:
4/14/2004 (peifenz) Merged genes AT3G01120/CGS1 into G-993/CGS1
11/21/2002 (mueller) Merged genes G-993/CGS1 and AT3G01120/AT3g01120


References

Kim02a: Kim J, Lee M, Chalam R, Martin MN, Leustek T, Boerjan W (2002). "Constitutive overexpression of cystathionine gamma-synthase in Arabidopsis leads to accumulation of soluble methionine and S-methylmethionine." Plant Physiol 2002;128(1);95-107. PMID: 11788756

Ravanel98: Ravanel S, Gakiere B, Job D, Douce R (1998). "Cystathionine gamma-synthase from Arabidopsis thaliana: purification and biochemical characterization of the recombinant enzyme overexpressed in Escherichia coli." Biochem J 1998;331 ( Pt 2);639-48. PMID: 9531508

Van03: Van Huysen T, Abdel-Ghany S, Hale KL, LeDuc D, Terry N, Pilon-Smits EA (2003). "Overexpression of cystathionine-gamma-synthase enhances selenium volatilization in Brassica juncea." Planta 218(1);71-8. PMID: 14618405


Report Errors or Provide Feedback
Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
Page generated by SRI International Pathway Tools version 18.5 on Mon Nov 24, 2014, BIOCYC13A.